This project has specific goals to: 1. analyze the functional consequences (in transcription and processing) of specific DNA sequences about the human globin genes, the hormonally responsive growth hormone genes, and constitutively expressed genes such as thymidine kinase; 2. utilize transformation systems to facilitate the isolation of genes expressed at exceedingly low levels in cells for which the now classical techniques of recombinant DNA are not likely to succeed. 3. examine the molecular nature of specific mutations selected in vivo and in vitro in cell culture in genes such as thymidine kinase, hypoxanthine guanine ribosyl transferase, adenine phosphoribosyl transferase. 4. examine the potential fluidity of the mammalian genome.